Balancing or stabilizing mechanism for vertically movable tank roofs



Jan. 22, 1957 J. H. wlGGlNs 2,778,719

BALANCING OR STABILIZING MECHANISM FOR VERTICALLY MOVABLE TANK ROOFSFiled June 12, 1952 /2 5 la TA/VEN TOR,

/ 6 ATTORNEY.

BALANCING R STABILIZING MECHANISM FOR VERTCALLY MOVABLE TANK ROOFS JohnH. Wiggins, Chicago, lll.

Application June 12, 1952, Serial No. 293,071

4 Claims. (Cl. 48-176) This invention relates to mechanisms ot the kindthat are used for balancing or stabilizing vertically movable tank roofswhich rise and fall in response to variations in the pressure of a gasor vapor on the underside of the roof.

VThe objects of my invention are to reduce the cost and number of parts,and simplify the installation and inspection of tank root` balancingmechanisms of the particular type that employ or are equipped with avertically movable guide means attached to the roof at the center ofsame and arranged in sliding engagement with a coacting, verticallydisposed, stationary guide means located at the center of the tank.

To this end l have devised a tank roof balancing mechanism of thegeneral type above referred to, that has the following essential anddistinguishing characteristics:

(a) The stationary guide means at the center of the tank consists of avertically disposed member that projects upwardly through an opening inthe' roof and terminates at a level high enough to ensure that it willcoact properly with a guide means carried by the roof even when the roofis in its highest position.

(b) The roofis provided with a housing means that encases the upper endportion of said stationary center guide member in all positions of theroof, and

(c)` The roof carries a guide means that coacts with said stationaryguide member and which is so arranged that it is accessible from the topside of the roof.

Other features Vof my improved mechanism that are advantageous but notessential to its successfuloperation, are that the plates of which theroof is constructed are utilized to constitute part of the balancingmechanism for the roof, and the framing-on which the roof rests when itis in its lowest position is utilized to constitute part of the roofbalancing mechanism.

Figure l of the drawings is a transverse vertical sectional viewillustrating a roof balancing or stabilizing mechanism constructed inaccordance with my invention.

Figure 2 is a top plan view of the roof showing certain parts of thebalancing mechanism in horizontal section on the line 2 2 of Figure 1,and Figure 3 is a vertical sectional view illustrating another way ofconstructing the guide means that is located above or on the top side ofthe roof.

In the drawings the reference character 5 designates a tank that isprovided with a vertically movable roof 1, herein illustrated as alifter type roof equipped with a depending skirt 2 that surrounds and isarranged in spaced relation with the tank side wall, the lower end ofsaid skirt being reinforced and strengthened by a stitener or equivalentmeans 3. vAny suitable means can be used to seal theV annularspace'between said skirt and the tank side wall such as a conventionalliquid seal or a curtain type seal formed by a gas tight flexibleelement 13 attached to the skirt on the roof and to the tank side wall,said sealing element being so designed as to permit the roof to movevertically from its extreme low position shown in full lines in Figurel, into its extreme high nited States Patent O position shown in brokenlines in said figure, in response to variations in the internal pressureof the gas or vapor space on the under side of the roof.

The preferred form of my improved balancing mechanism hereinillustrated, briefly described, consists of a stationary, verticallydisposed guide member arranged at the center of the tank with its upperend portion projecting upwardly through an opening in the roof, a guidemeans carried bythe roof and accessible from the top side of same andconstructed in such a manner that when the roof tilts or goes out ofbalance said guide means will exert a lateral thrust on the portion ofsaid stationary guide members located above the roof a housing on theroof for encasing the portion of said stationary center guide whichprojects above the roof, a load member of relatively great weightarranged in telescoped relation with the stationary, vertically disposedguide member at the center of the'tank, a group of radially disposedpull down devices formed by cable, chains or rods that suspend said loadmember from the underside of the peripheral portion of the roof andmaintain said loa-d member in Widely spaced, vertical relation with thepreviously mentioned guide means mounted on or adjacent the top v anannular weight 7 that surrounds the stationary guide l member 15, saidWeight being suspended from the roof side of the roof, a circular beamattached to the periphery of the roof and extending circumferentiallyaround the same, and a group of radially disposed roof rafters attachedat their outer ends to the top edge of the side wall of the tank andattached at their inner ends to the stationary vertically disposed guidemember in the tank. When the roof tilts or goes out of balance the loadmember suspended from the roof exerts a lateral thrust on the stationaryguide member in a direction diametrically opposite to the lateral thrustexerted on said stationary guide member by the guide means carried byand accessible from the top sideV of the roof. For convenience kI Willrefer to the guide means accessible from the top side of the roof, asthe top guide, and l will refer to lthe load member which is suspendedfrom the underside of the roof as the weight i In the form of myinvention herein illustrated, the

above mentioned stationary, vertically disposed guide memberis formed bya tubular post 15 Whose lower end is securely anchored to the bottom 6of the tank 5 and whose upper end portion 14 projects upwardly throughan opening at the center of the roof 1. The roof is prolvided with a topguide illustrated on Figures 1 and 2 as being formed by a plurality ofrollers 10 that are rotatably mounted on brackets 11 carried by ahousing member 12 which is rigidly attached to the top side of the roof1 so as to surround the center opening in the roof through which thestationary guide member l5 projects upwardly, the yrollers l0 being soarranged that when the roof tilts or goes out'of balance there will be.some portion of the guide means on the top side of the roof that exertslateral pressure on a portion of the stationary center guide memberwhich is located above the roof, this being true both when the roof isin its extreme low position shown in full lines in Figure l, and in itsex' relation with the roof is provided with a removable cap or topportion 4 so as to facilitate the installation, inspection and servicingof the rollers l0.

The previously mentioned load member suspended from the roof, is hereinillustrated as being formed by by a plurality of radially disposed pulldown devices or tension members, formed by chains or cables or by rods 8attached at their lower ends to the weight 7 and leading upwardly andoutwardly from same to the periph- Patented Jan, 22, 1957V` eral portionof the roof to which the upper ends of said rods are attached by lugs onthe underside of the roof located some distance inwardly from theperipheral edge of the roof.

The upper end portion of the side wall of the tank is reinforced andstrengthened preferably by means of a curb 18 that extendscircumferentially around the top edge of said side wall, and thestationary center guide member 15 is anchored to the tank side wall byradially disposed roof rafters 9 disposed so as to serve as a supportingstructure for the roof when the roof is in its extreme low position. Asshown in Figure l, the roof is provided at its peripheral edge with areinforcing member 19 that coacts with the roof plates and with theskirt 2 of the roof to form an annular beam which extendscircumferentially around the roof.

When the roof is supported by the rafters 9 or by gases confined in thetank, and the roof is subjected to no forces such as wind pressure or asnow load that tips the roof or throws it out of balance, all of therods 8 have the same tension. The horizontal components of thesetensions at the upper ends of said rods are directed to the center ofthe roof and these are all equal and are balanced through the circularbeam 19 at the periphery of the roof. Hence it is not necessary that therollers lil or equivalent top guide of the roof be in direct bearingengagement with the upper end portion 14 of the stationary guide member15 at such times, as they perform no function in stabilizing orbalancing the roof. Also under the condition mentioned the horizontalcomponents of the tensions at the lower ends of the rods 8 are all equaland are balanced through the weight 7, with the result that the weight 7is maintained in such relation with the stationary guide member 15 thatsaid weight exerts no side pressure or lateral thrusts on saidstationary guide member. When a foreign load, such for example as a snowload designated by the reference character 16, is applied to the leftside of the roof, then the rods 8 at the right hand side of the tankpull harder than normal and the rods 8 at the left hand side of the tankpull less than normal. This gives an increased horizontal forcecomponent at the right side, directed towards the center as indicated bythe large arrow 17 in Figure l. This load passes around the peripheralportion of the roof, which acts as a circular beam and compressionmember, t a point which is near the foreign load 16 on the roof, asindicated by the smaller arrows 17 in Figure 2. Then this same loadpasses in tension, designated by the arrows 2b in Figure 2, through theroof plates to the center of the roof and this same load 17 is thenapplied to the roller 10 on the right side of the top portion 14 of thestationary guide member 15. This exerts a lateral thrust on the portion14 of the stationary center guide member which tends to push saidportion 14 to the left. However, as the stationary center guide memberis prevented by the roof rafters 19 from moving laterally, this sameload 17 is then carried into the top curb member 1S at the top edge ofthe tank side wall. At the same time there is a horizontal componentdirected as shown by the arrow 21 in Figure l. This is resisted by thestationary center guide Whose lower end is securely anchored to thebottom of the tank.

In Figure 3 I have illustrated another Structure that may be used toconstitute the top guide on the roof. In said structure the upper endportion 14 of the stationary center guide member is provided at its topwith a plurality of rollers lila which are adapted to engage or bearagainst a housing member 12a rigidly attached to the top side of theroof and projecting upwardly from same, said housing member 12a beingpreferably provided with a removable cap 4a.

From the foregoing it will be understood that in my improved structuresubstantially the total top portion of the roof guiding means of themechanism, is located above the top side of the roof, and is formed by aportion of the stationary center guide that projects upwardly throughthe roof, coacting guide rollers that are accessible from the top sideof the roof, and a housing on the top side of the roof that encases theportion of the center guide member projecting above the roof and which,in whole or in part, is formed by a member rigidly attached to the roof.Also in my mechanism the metal plates of which the roof is constructedand the rafters on whichthe roof rests when it is in its lowestposition, are utilized to constitute part of the mechanism relied uponto restore the roof to its normal position in the event it tips orbecomes unbalanced. Hence l reduce the parts necessary for a roofbalancing mechanism to a very minimum and accordingly reducetremendously the cost of the structure.

Having thus described my invention, that l claim as new and desire tosecure by Letters Patent is:

l. In a tank having its upper end closed by a disclike roof that isvertically movable with respect to the tank in order to vary theinternal Volume of the tank beneath the roof, the combinationcomprising, an upstandingsubstantially rigid vertical guide post fixedat its lower end at the center of the tank and having its upper endportion extending through an opening in the center of the roof, rollermeans for guiding said roof upon said post for articulate tiltingmovements with respect thereto and also for guided vertical movementsalong said post, said roller means being so constructed and arranged asfreely to accommodate tilting movement of said roof with respect to saidpost and with respect to the horizontal when an unbalancing off-centerload is applied to said roof, an upwardly extending housing hermeticallycovering said opening in said root and containing said roller means,said upper portion of said post extending upwardly into said housing,and an annular balancing weight for said roof encompassing said post andarranged for guided vertical sliding movements thereon, said annularbalancing weight being of substantial mass and being suspended beneathsaid roof solely from the peripheral portion thereof by a plurality ofsubstantially equally spaced flexible suspension members having theirrespective upper ends secured to said peripheral portion of said roof atcircumferentially spaced locations thereon and having their lower endssecured to said weight, the mass `of said balancing weight tending tomaintain said roof in a horizontal attitude and causing said roof toreturn to said horizontal attitude when an unbalancing off-center loadis removed from said roof.

2. The combination set forth in claim l, wherein said rollermeansincludes a plurality of rollers mounted upon the interior Wall ofsaid housing for rolling contact with said upper portion of said post.

3. The combination set forth in claim 1, wherein said roller meanscomprises a plurality of rollers mounted upon said upper portion of saidpost for rolling contact with the interior wall of said housing.

4. The combination set forth in claim l, wherein said housing isprovided with a doorway permitting ready access to said roller means.

References Cited in the le of this patent UNITED STATES PATENTS 628,868Strom Iuly 11, 1899 666,598 Bryan Jan. 22, 1901 2,194,581 Weichsel Mar.26, 1940 2,360,692 Larsen Oct. 17, 1944 2,452,146 Plummer Oct. 26, 19482,497,851 Allen Feb. 21, 1950

1. IN A TANK HAVING ITS UPPER END CLOSED BY A DISCLIKE ROOF THAT ISVERTICALLY MOVABLE WITH RESPECT TO THE TANK IN ORDER TO VARY THEINTERNAL VOLUME OF THE TANK BENEATH THE ROOF, THE COMBINATIONCOMPRISING, AN UPSTANDING SUBSTANTIALLY RIDID VERTICAL GUIDE POST FIXEDAT ITS LOWER END AT THE CENTER OF THE TANK AND HAVING ITS UPPER ENDPORTION EXTENDING THROUGH AN OPENING IN THE CENTER OF THE ROOF, ROLLERMEANS FOR GUIDING SAID ROOF UPON SAID POST FOR ARTICULATE TILTINGMOVEMENTS WITH RESPECT THERETO AND ALSO FOR GUIDED VERTICAL MOVEMENTSALONG SAID POST, SAID ROLLER MEANS BEING SO CONSTRUCTED AND ARRANGED ASFREELY TO ACCOMMODATE TILTING MOVEMENT OF SAID ROOF WITH RESPECT TO SAIDPOST AND WITH RESPECT TO THE HORIZONTAL WHEN AN UNBALANCING OFF-CENTERLOAD IS APPLIED TO SAID ROOF, AN UPWARDLY EXTENDING HOUSING HERMETICALLYCOVERING SAID OPENING IN SAID ROOF AND CONTAINING SAID ROLLER MEANS,SAID UPPER PORTION OF SAID POST EXTENDING UPWARDLY INTO SAID HOUSING,AND AN ANNULAR BALANCING WEIGHT FOR SAID ROOF ENCOMPASSING SAID POST ANDARRANGED FOR GUIDED VERTICAL SLIDING MOVEMENTS THEREON, SAID ANNULARBALANCING WEIGHT BEING OF SUBSTANTIAL MASS AND BEING SUSPENDED BENEATHSAID ROOF SOLELY FROM THE PERIPHERAL PORTION THEREOF BY A PLURALITY OFSUBSTANTIALLY EQUALLY SPACED FLEXIBLE SUSPENSION MEMBERS HAVING THEIRRESPECTIVE UPPER ENDS SECURED TO SAID PERIPHERAL PORTION OF SAID ROOF ATCIRCUMFERENTIALLY SPACED LOCATIONS THEREON AND HAVING THEIR LOWER ENDSSECURED TO SAID WEIGHT, THE MASS OF SAID BALANCING WEIGHT TENDING TOMAINTAIN SAID ROOF IN A HORIZONTAL ATTITUDE AND CAUSING SAID ROOF TORETURN TO SAID HORIZONTAL ATTITUDE WHEN AN UNBALANCING OFF-CENTER LOADIS REMOVED FROM SAID ROOF.